Ultrasound phantom models, materials, and methods

ABSTRACT

Devices, systems, and methods appropriate for use in medical training that include materials that better mimic natural human tissue are disclosed. In one aspect a polysiloxane mixture for simulating human biological tissue, especially human breast tissue, is disclosed. In another aspect, a method of manufacturing a biological tissue ultrasound phantom is disclosed. In another aspect, a human breast tissue models are disclosed. In some instances, the human breast tissue model includes at least one simulated pathological structure that simulates such pathologies as a cyst, a medullary carcinoma, a ductal carcinoma, an infiltrating scirrhus carcinoma, a lobular carcinoma, and a fibroadenoma.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a non-provisional application that claimspriority to U.S. Provisional Patent Application No. 61/305,982 filedFeb. 19, 2010 and titled “Polysiloxane Materials and Methods that MimicTissue,” which is hereby incorporated by reference in its entirety. Thepresent application is related to U.S. patent application Ser. No.______, filed Feb. 18, 2011 and titled “BREAST TISSUE MODELS, MATERIALS,AND METHODS” (Attorney Docket No. 16844.125), which is herebyincorporated by reference in its entirety.

BACKGROUND

As medical science has progressed, it has become increasingly importantto provide non-human interactive formats for teaching patient care.Non-human interactive devices and systems can be used to teach theskills needed to successfully identify and treat various patientconditions without putting actual patients at risk. Such trainingdevices and systems can be used by medical personnel and medicalstudents to learn the techniques required for proper patient care. Thetraining devices and systems can also be used by patients to learn theproper way to perform self-examinations.

As the use of non-human interactive training formats has increased, theneed for materials that simulate natural human tissue has alsoincreased. There have been earlier attempts to mimic characteristics ofnatural human tissues. For example, U.S. Patent Application PublicationNo. 2008/0076099 discloses human tissue phantoms and associated methodsof manufacturing that utilize two-component silicone gels covered by anylon fabric. Also, U.S. Pat. No. 5,805,665, U.S. Pat. No. 4,277,367,U.S. Pat. No. 5,902,748, and U.S. Pat. No. 6,675,035 each disclosevarious materials intended to simulate imaging properties of humantissue for various types of imaging techniques. Further, U.S. Pat. No.6,945,783 discloses a breast examination training system with inflatablenodules that simulate tumors within the breast tissue. While theseearlier attempts at mimicking aspects of natural human tissue have beenadequate in some respects, they have been inadequate in many respects.Accordingly, there remains a need for materials that better mimicnatural human tissue. In that regard, the training of medical personneland patients is greatly enhanced through the use of realistic hands-ontraining with devices and systems, such as those of the presentdisclosure, that better mimic characteristics of natural human tissuethan previous materials.

Polysiloxanes are the most common and one of the most importantorganosilicon polymers used in polymer chemistry. The silanol, SiO(Me)₂,is the key functional group in the synthesis of these polymers. It isvery important to understand the chemistry of the individual elements ofthe polymer as well as the behavior of the functional group in order tounderstand the characteristics of polysiloxane polymers.

Silicon is a Group 4 (IVA) element found in the periodic table beneathcarbon, and it is, by far, the most abundant element in the Group 4elements. Some of its characteristics are similar to carbon, but overallit can be seen as a completely different element. It makes up 27% of theearth's crust by mass, and it is second in abundance in the world (afteroxygen). Silicon has semi-metallic properties, thus, it is important inthe semiconductor industry with wide ranges of applications in computersand solar energy collection. It is very rare to find silicon by itselfin nature; it is usually bound to oxygen as either SiO₂ or SiO₄. Silicondioxide has many forms found in nature, the most common being quartz, amajor constituent of sandstone and granite, as well as being a majorcomponent of glass.

Silicon bonding can be compared to carbon bonding in many ways. Carbonis the backbone of life and can form chains of infinite length. Silane,SiH₄, and methane, CH₄, are both very stable tetrahedral compounds. Asyou build chains, however, the carbon chain is stable but the silanechains' stability decreases with length. This is due to many factors: 1)the Si—Si bond is slightly weaker than the C—C bond, 2) the Si—H bond isweaker than the C—H bond, 3) silicon is less electronegative thanhydrogen while carbon is more electronegative than hydrogen, and 4)silicon is larger, providing greater surface area, and has low lying dorbitals, which promotes nucleophilic attack.

Polysiloxanes are known for their useful properties, such asflexibility, permeability to gases, low glass transition temperature,T_(g), and low surface energy. Polysiloxanes exhibit two types offlexibility: torsion flexibility and bending flexibility. Torsionflexibility is the ability of the atoms to rotate around a chemicalbond. Bending flexibility occurs when there is a large hindrance betweennon-bonded atoms where there are unfavorable torsion angles.

In view of the foregoing, there remains a need for devices, systems, andmethods appropriate for use in medical training that include materialsthat mimic natural human tissue.

SUMMARY

Devices, systems, and methods appropriate for use in mimicking naturalhuman tissue are disclosed. Generally, the materials of the presentdisclosure are utilized to simulate natural tissue and, in particular,natural human tissue. In some instances, the materials of the presentdisclosure have particular application in the field of medicalsimulation. In some instances, the materials of the present disclosureprovide a lifelike feel to simulated human skin and underlying tissue.

In one aspect a polysiloxane mixture for simulating human biologicaltissue is disclosed. The mixture comprises a silicone foam and asilicone oil, where the silicone foam and the silicone oil are combinedin a manner such that the resulting mixture has physical materialproperties simulating a natural human biological tissue. In someinstances, the silicone foam is present in an amount of about 10 to 45percent by weight of the total mixture weight, while the silicone oil ispresent in an amount of about 55 to 90 percent by weight of the totalmixture weight. In one particular instance, the silicone foam is presentin an amount of about 25 percent by weight of the total mixture weight,while the silicone oil is present in an amount of amount of about 75percent by weight of the total mixture weight. The silicone oil has aviscosity of about 30 to 500 centipoise in some embodiments. The siliconoil has a low molecular weight silicone oil in some embodiments. Thesilicone foam is a closed cell silicone foam in some embodiments. Insome instances, the polysiloxane mixture further comprises a siliconethermoset. In some embodiments, the silicone foam and the siliconethermoset comprise a platinum catalyzed silicone. In some embodiments,the resulting polysiloxane mixture has physical material propertiessimulating the natural human biological tissue, including ultrasoundproperties such that ultrasound equipment typically used to visualizethe natural human biological tissue can be used in a similar manner tovisualize the resulting mixture. In some instances, the ultrasoundmaterials of the present disclosure do not include a silicone foam.

In another aspect, a method of manufacturing a biological tissue phantomis disclosed. The method comprises mixing a silicone oil with a siliconefoam to form a blend, pouring the blend into a mold, stirring the blenduntil a foaming reaction starts, and allowing the blend to cure. Thecured blend has physical material properties simulating a natural humanbiological tissue and in some instances, human breast tissue. In someinstances, the method includes adding a silicone thermoset to reduce andquantity of the foam cells. In some embodiments, the silicone foam is atwo-component platinum silicone foam. In some embodiments, the siliconeoil is a low molecular weight silicone oil. In some instances, theamount of silicone oil that is mixed is about three times the amount ofthe silicone foam.

In another aspect, a human breast tissue model is disclosed. The humanbreast tissue model comprises a simulated breast tissue comprising amixture of a silicone foam and a silicone oil and a simulated skin layercovering the simulated breast tissue. The simulated skin layer comprisesa silicone thermoset. The simulated breast tissue and the simulated skinlayer are sized and shaped to mimic a natural human breast. In someinstances, the human breast tissue model includes at least one simulatedpathological structure imbedded within the simulated breast tissue. Theat least one simulated pathological structure is formed of a materialdifferent than the simulated breast tissue. In some embodiments, atleast one simulated pathological structure simulates a pathologyselected from a group consisting of a cyst, a medullary carcinoma, aductal carcinoma, an infiltrating scirrhus carcinoma, a lobularcarcinoma, and a fibroadenoma. In some instances, the at least onesimulated pathological structure is formed of a silicone thermoset. Inone embodiment, the at least one simulated pathological structure isformed of a silicone thermostat having a shore hardness of about 10 A.In some instances, the human breast tissue model includes at least onesimulated anatomical structure imbedded within the simulated breasttissue at an anatomically appropriate location. In some embodiments, atleast one simulated anatomical structure simulates an anatomicalstructure selected from a group consisting of a lymph node, a pectoralismuscle, and a rib. In some instances, the human breast tissue modelincludes a fastener attached to a portion of the human breast tissuemodel. In some embodiments, the fastener is configured to allow thehuman breast tissue model to be affixed to a base. In some instances,the base is a female torso or manikin.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure can be better understood from the followingdetailed description when read with the accompanying figures.

FIG. 1 is a front view of a breast tissue model according to one aspectof the present disclosure.

FIG. 2 is a cross-sectional side view of the breast tissue model of FIG.1.

FIG. 3 is a perspective view of a pair of breast tissue models accordingto one aspect of the present disclosure.

FIG. 4 is a front view of a breast tissue model according to anotheraspect of the present disclosure.

FIG. 5 is a perspective view of a molding system for forming a breasttissue model according to an aspect of the present disclosure.

FIG. 6 is a perspective view of a mother mold of the molding system ofFIG. 5.

FIG. 7 is a top view of the mother mold of FIG. 6.

FIG. 8 is a cross-sectional side view of the mother mold of FIGS. 6 and7, taken along section line 8-8 of FIG. 7.

FIG. 9 is a perspective view of a glove mold of the molding system ofFIG. 5.

FIG. 10 is a top view of the glove mold of FIG. 9.

FIG. 11 is a side view of the glove mold of FIGS. 9 and 10.

FIG. 12 is a cross-sectional side view of the glove mold of FIGS. 9-11,taken along section line 12-12 of FIG. 10.

FIG. 13 is a top view of the mother mold of FIGS. 6-8 and the glove moldof FIGS. 9-12 assembled together.

FIG. 14 is a cross-sectional side view of the assembled mother mold andglove mold of FIG. 13, taken along section line 14-14 of FIG. 13.

FIG. 15 is an ultrasound rendering of an ultrasound phantom of thepresent disclosure showing the presence of a simulated solid mass.

FIG. 16 is a close-up view of the solid mass of the ultrasound renderingof FIG. 15.

FIG. 17 is an ultrasound rendering of an ultrasound phantom of thepresent disclosure showing the presence of a simulated translucent mass.

FIG. 18 is a close-up view of the translucent mass of the ultrasoundrendering of FIG. 17.

FIG. 19 is schematic diagram of an ultrasound phantom according toanother embodiment of the present disclosure.

FIG. 20 is an ultrasound rendering of an ultrasound phantom of thepresent disclosure showing the presence of a simulated cyst.

FIG. 21 is a close-up view of the cyst of the ultrasound rendering ofFIG. 20.

FIG. 22 is an ultrasound rendering of the ultrasound phantom of FIGS. 20and 21 showing the introduction of a needle for aspirating the cyst.

FIG. 23 is a close-up view of the cyst and needle of the ultrasoundrendering of FIG. 22.

FIG. 24 is an ultrasound rendering of the ultrasound phantom of FIGS.20-23, showing the fully aspirated cyst.

FIG. 25 is a close-up view of the fully aspirated cyst of the ultrasoundrendering of FIG. 24.

FIG. 26 is an ultrasound rendering of an ultrasound phantom of thepresent disclosure showing the presence of a plurality of cysts.

FIG. 27 is an ultrasound rendering of an ultrasound phantom forsimulating a vessel according to another aspect of the presentdisclosure.

FIG. 28 is a schematic diagram of a vessel simulator according to anembodiment of the present disclosure.

FIG. 29 is an end view of the vessel simulator of FIG. 28.

FIG. 30 is an end view of the vessel simulator of FIG. 28 similar tothat of FIG. 29, but showing deformation of a surface of the vesselsimulator.

FIG. 31 is an ultrasound rendering of the vessel simulator of FIGS.28-30 from a cross-sectional view.

FIG. 32 illustrates ultrasound renderings of the vessel simulator ofFIGS. 28-30 from two opposing side longitudinal views.

FIG. 33 is a schematic diagrammatic cross-sectional view of a vesselsimulator according to another embodiment of the present disclosure.

FIG. 34 is a schematic diagram top view of a vessel simulator accordingto another embodiment of the present disclosure.

FIG. 35 is an ultrasound rendering of an ultrasound phantom according toone aspect of the present disclosure.

FIG. 36 is an ultrasound rendering of an ultrasound phantom according toanother aspect of the present disclosure.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention is directed to polysiloxane materials that haveunique physical properties that mimic biological tissue, including verylow flexural modulus (tendency for a material to bend), exceptionalresilience (the power or ability to return to original form or positionafter being bent, compressed, or stretched; elasticity), and selfsealing characteristics (ability to automatically seal punctures).Products that are properly constructed from these materials inaccordance with the present disclosure provide properties that includethe tactile properties, ultrasound properties, and resilient propertiesof biological tissue. The products formed from the inventive materialssimulate real skin and tissue, and are resistant to deterioration, evenafter repeated puncture by needles and other medical instruments. Theproducts formed from the inventive materials of the present disclosurecan also advantageously mimic aspects of real medical procedures, e.g.,natural closure of a puncture. The materials of the present disclosureprovide lower flexural modulus with greater recovery than materialspreviously used to recreate the look and feel of biological tissue.

One purpose of the inventive materials and methods described herein isthe production of simulators for use in medical procedure andexamination technique training. Other uses contemplated, however,include any application that requires the feel and appearance of animaltissue, especially human tissue. Such applications include, withoutlimitation, puppets, taxidermy, robotics, and sex toys.

The materials of the present invention include a mixture of at least twopolysiloxane or silicone materials (1) a silicone foam or gel and (2) asilicone oil or fluid. The combination of the oil with the foam producesa material that feels and acts surprisingly similar to certainbiological tissue. The present disclosure provides materials that mimicthe feel of human tissue and provides materials that mimic theultrasound properties of human tissue. A material formed of a siliconefoam and a silicone oil or fluid produces a material that is very softand flexible and mimics the feel of certain human tissues, such as thesoftness of a human breast. This material is not as useful as a matrixfor ultrasound as other materials of the present disclosure due to theair encapsulated in the foam. However, the material is very useful as atarget in an ultrasound applications. For example, in some instances itis utilized as a target within a material formed of silicone gel, fusedsilica, and silicone fluid, which has excellent properties for use as anultrasound matrix (as well as targets within the ultrasound matrix).

As used herein, the term “silicone foam” designates a polyorganosiloxanecomposition in the form of a foam. Silicone foam is produced by acondensation reaction between a siloxane polymer containing silanol(Si—OH) groups and crosslinkers containing silane (Si—H) groups,typically in the presence of a catalyst. When these compounds are mixedand reacted together, the formation of siloxane linkages (Si—O—Si)occurs, liberating hydrogen gas, which acts as the blowing agent to makethe material into foam. Because of its high silicone content, siliconefoam is typically less flammable than flexible polyurethane foam.

The foamable silicone compositions according to the present inventionmay be any of those which are commercially available that include anorganosilicon polymer including siloxane units having a silicon-bondedhydrogen atom, a hydroxy bearing material, for example an organosiliconpolymer including siloxane units providing silicon-bonded hydroxylgroups, and a catalyst, for example a tin compound or more preferably anoble metal compound or complex. These compositions cure according tothe scheme OH+≡Si—H-->≡Si—O+H₂. A polymeric material reactive with thesilicon-bonded hydrogen atoms, for example an organosilicon polymerhaving silicon-bonded hydroxyl and/or unsaturated e.g., vinyl groups,may be included in the mixture so that a network of interconnectedpolysiloxane chains is produced and the hydrogen evolved as a gas servesto form cells within the developing network. Preferred foam forming,curable organosilicone polymer compositions include apolydiorganosiloxane having silicon-bonded unsaturated, e.g., vinylgroups, available for reaction with polysiloxanes having silicon-bondedhydrogen atoms. The addition reaction that occurs is appropriate toyield chain extended or crosslinked elastomeric silicone products, butdoes not generate volatile materials for causing foaming in the curingcomposition. The foaming may be achieved by chemical reaction of thesilicon-bonded hydrogen atoms with silicon-bonded hydroxyl groups and/orwater or an aliphatic alcohol, or by inclusion in the composition of avolatile blowing agent. The polysiloxanes and other ingredients and theproportions thereof are selected so that the network is sufficientlydeveloped and cured to produce a resilient foam of desired cellularstructure within a short period of time, on the order of a few minutesor less.

Suitable polysiloxanes include siloxane units having a silicon-bondedhydrogen atom include polysiloxanes having units according to thegeneral formula

R_(p)HSiO_((3−p)/2)

in which each R represents a monovalent hydrocarbon group containing 1to 20 carbon atoms, for example a lower alkyl or phenyl group, e.g., amethyl group, and p is 1 or 2. The polysiloxanes may also comprise units(i)

R_(n)SiO_((4−n)/2)

in which R is as referred to above and n is 1, 2 or 3. Preferably, thepolysiloxane has from 0.3% to 2.5% by weight of silicon-bonded hydrogenatoms. Each R preferably represents a methyl group. Preferably, terminalgroups of the polysiloxane have the formula R₃SiO_(1/2), where each Rrepresents a methyl group. Suitable polysiloxanes include thosecomprising MeHSiO units with or without the presence of Me₂SiO (where Merepresents a methyl group) units and having viscosities on the order offrom about 1 to about 1000 mm²/s, more preferably from about 5 to about50 mm²/s.

Suitable polysiloxanes having silicon-bonded unsaturated, e.g., vinylgroups available for reaction with polydiorganosiloxanes havingsilicon-bonded hydrogen atoms include polysiloxanes having siloxaneunits according to the general formula

R_(m)R′SiO_((3−m)/2)

in which each R represents a monovalent hydrocarbon group having up to20 carbon atoms, for example a lower alkyl or phenyl group, e.g., amethyl radical, m is 1 or 2 and R′ represents an aliphaticallyunsaturated group for example cyclohexenyl or a group CH═CHR″ linked tothe silicon atom, for example via a divalent aliphatic chain wherein R″represents a hydrogen atom or an alkyl group for example vinyl, allyl orhexenyl. These polysiloxanes also comprise units (i) in which R and nare as referred to above. These materials are reactive with thesilicon-bonded hydrogen atoms in presence of a noble metal catalyst by ahydrosilylation reaction and thus contribute to the polysiloxane matrix.Preferably these polysiloxanes have from 0.0002% to 3% by weight ofaliphatically unsaturated groups and n is such that they have aviscosity on the order of about 10 mm²/s to about 500,000 mm²/s.Preferred compositions employ a polysiloxane having siloxane unitsaccording to the general formula

R_(m)R′SiO_((3−m)/2)

in which R′ represents a group CH═CH₂ linked to the silicon atom via adivalent aliphatic chain and having a viscosity in the range 100 mm²/sto 2000 mm²/s.

Suitable organosilicon polymers including siloxane units providing asilicon-bonded hydroxyl group include polydiorganosiloxanes having atleast two siloxane units of the formula

R_(a)Q_(b)SiO_((4−(a+b))/2)

in which a has a value of 0, 1 or 2, b has a value of 1 or 2 and the sumof a+b is not greater than 3, Q represents a hydroxyl group for examplesilanol terminated polydiorganosiloxanes according to the generalformula HO((R₂)SiO)_(s)H in which each R represents a methyl group and shas a value from about 10 to about 1200. Suitable materials haveviscosities on the order of about 10 mm²/s to about 500,000 mm²/s.Preferred compositions which provide the more elastomeric foams employpolydiorganosiloxanes according to the general formula HO((R₂)SiO)_(s)Has aforesaid which have viscosities on the order of about 2,500 mm²/s toabout 20,500 mm²/s. The density of the silicone foam can besignificantly reduced without degrading its structural strength byincluding a short-chain silanol terminated polydiorganosiloxane in theformulation. Preferred compositions employ polydiorganosiloxanesaccording to the general formula HO((R₂)SiO)_(s)H as aforesaid in whichs has a value from about 2 to about 10. Preferred materials haveviscosities on the order of about 5 mm²/s to about 100 mm²/s.

Polydiorganosiloxanes having at least two siloxane units of the formula

R_(a)Q_(b)SiO_((4−(a+b))/2)

in which Q is a hydroxyl bearing alkylene or oxyalkylene chain may alsobe used. The chain may be attached to the silicon atom in any convenientway but is preferably linked to the silicon atom by a carbon atom.Suitable hydroxyl bearing chains include those containing up to 50 chainatoms. Suitable alkylene chains are those having 1 to 15, morepreferably 4 to 10 chain carbon atoms. Suitable oxyalkylene chainsinclude those of the formula (C_(d)H_(2d)O)_(e)H in which d has thevalue 2, 3 or 4 and e has a value in the range of 1 to 15 and morepreferably in the range of 1 to 10, i.e., having from 1 to 15 and, morepreferably, 1 to 10 oxyalkylene groups. The oxyalkylene groups may befor example oxyethylene, oxypropylene or oxybutylene or mixturesthereof, the most preferred being the oxyethylene group. Thispolydiorganosiloxane also comprises siloxane units (i) as aforesaid.Other materials that may be included as crosslinking agents includematerials having three or more functional e.g., hydroxy groups permolecule.

The foam compositions for use in the present invention preferablyinclude one or more alcohols. These materials influence the structure ofthe foams formed by use of the composition and yield cured foams of lowdensity. The alcohol is selected with a view to contributing not only tothe generation of hydrogen gas, but also with a view to achievingdesired resilience of the foam. Suitable alcohols include the primaryaliphatic and araliphatic alcohols for example the lower aliphatic monofunctional alcohols having up to 8 carbon atoms, e.g., ethanol,propanol, butanol and benzyl alcohol. Foams of lowest density are formedby use of the aliphatic alcohols having from 2 to 12 chain carbon atoms.Preferred compositions employ n-propanol.

Compositions suitable for use in the invention also preferably employ afoam stabiliser or surfactant. Suitable foam stabilizing materialsinclude fluorinated silicones, for example a polyorganosiloxanecomprising

(CF₂)_(m)(CH₂)_(n)O_(p)SiO_((4−p)′/2)

R₃SiO_(1/2), SiO_(4/2) units and silicon bonded hydroxyl groups whereineach R represents a monovalent hydrocarbon group containing from 1 to 20carbon atoms, m is an integer having an average value of from 1 to 20, nhas the value 1 or 2, p has the value 1, 2, or 3. The polysiloxane mayalso include from 0 to 10 percent, based on the weight of saidpolyorganosiloxane, of GSiO_(3/2) units wherein G represents the residueobtained by removing the hydrogen atom from a hydroxyl group of a linearorganic polymer selected from the group consisting of homopolymers ofethylenically unsaturated alcohols, copolymers of these alcohols withethylenically unsaturated hydrocarbons, polyethers and polyoxyalkyleneglycols, wherein said organic polymer contains an average of at leastone terminal hydroxyl group per molecule. These materials may beprepared by treatment of hexamethyldisiloxane coated polysilicates withthe alcohol F(CF₂)₈CH₂CH₂OH. They serve to stabilize the structure ofthe foam during its curing.

Suitable noble metal catalysts for use in the foamable compositionsinclude rhodium and platinum containing materials. Platinum catalystsmay take any of the known forms, ranging from platinum as deposited oncarriers such as silica gel or powdered charcoal to platinic chloride,salts of platinum and chloroplatinic acids. A preferred form of platinumis chloroplatinic acid either as the commonly obtainable hexahydrate orthe anhydrous form, on account of its easy dispersibility inorganosilicon systems and its non-effect on color of the mixture.Platinum complexes may also be used, e.g., those prepared fromchloroplatinic acid hexahydrate and divinyl tetramethyldisiloxane.Compositions according to the invention foam and cure very rapidly whenthe component parts have been mixed together. If it is desired toprolong the cure time, for example if it is desired to mix thecomposition and then transfer it to the site where it is intended tofoam and cure, one may include in the composition one of the knownplatinum catalyst inhibitors such as a polymethylvinylsiloxane cycliccompound or an acetylenic alcohol, e.g., methyl butynol. Largerproportions of catalyst may be used when a faster cure is desired.

There are no special limitations with regard to the types of siliconeoil used in the present invention. The silicone oil generally has aviscosity between about 50 cps and about 400 cps. The silicone oil mayhave a completely linear, partially-branched linear, cyclic, or abranched-chain molecular structure. The most preferable is a linear or acyclic molecular structure, with a low molecular weight. For example,the silicone oil can be a dimethylpolysiloxane having both molecularterminals capped with trimethylsiloxy groups, a methylphenylpolysiloxanehaving both molecular terminals capped with trimethylsiloxy groups, acopolymer of methylphenylsiloxane and dimethylsiloxane having bothmolecular terminals capped with trimethylsiloxy groups, a copolymer ofmethyl (3,3,3-trifluoropropyl) siloxane and dimethylsiloxane having bothmolecular terminals capped with trimethylsiloxy groups, a cyclicdimethylsiloxane, or a cyclic methylphenylsiloxane. For example, thesilicone oil can be an oil similar to those mentioned above, such as, adimethylpolysiloxane having both molecular terminals capped withdimethylvinylsiloxy groups, a copolymer of methylvinylsiloxane anddimethylsiloxane having both molecular terminals capped withdimethylvinylsiloxy groups, a methylvinylpolysiloxane having bothmolecular terminals capped with trimethylsiloxy groups, or a cyclicmethylvinylsiloxane. It is preferred that the silicone oil have aviscosity of 1 to 100,000,000 centipoise, preferably 2 to 10,000,000centipoise, more preferably 25 to 1,000 centipoise, and most preferably50 to 300 centipoise at 25° C. Preferred examples of silicone oil arepolydimethylsiloxane and simethicone.

In an exemplary embodiment, the silicone mixture includes a siliconeclosed cell foam blended with a low molecular weight silicone oil. Theaddition of the low molecular weight silicone oil to the closed cellsilicone foam produces a material with exceptional low modulus, i.e.,very flexible in a manner that is similar to natural human tissue. Thismixture of silicone materials also provides a product that has a recoilsimilar to human tissue.

To make the silicone mixture, typically one part silicone foam (e.g.,Smooth-On Soma Foama® 15 and three parts silicone oil (e.g., BJBEnterprises TC-5005-C or SilPak F-100 is prepared. The silicone oil isfirst mixed with part A of the foam. In some embodiments, the siliconefoam cell structure produces a specific gravity of 0.15 to 0.30 g/cm³,processing with the silicone oil. This mixture is then blended with partB of the foam until thoroughly mixed. The resulting blend is then pouredinto a mold cavity or the product cavity and is stirred until thefoaming reaction starts. The stirring is discontinued.

In some applications, a third component, such as a soft siliconethermoset is added. Generally, the silicone thermoset has a lowdurometer hardness, which is between about 0010 and about 0040 in someinstances. In some embodiments, Smoothon Ecoflex 0010 is utilized. Theaddition of the silicone thermoset reduces the quantity of foam cellspresent. In some instances, when the resulting product is to be anultrasonic phantom, the foam can be eliminated by use of a soft siliconethermoset if the desired physical properties of the foam are not needed.

The materials of the present disclosure have similar ultrasonicproperties to natural human tissue such that ultrasound machines andequipment typically used for examining natural human tissue maysimilarly be used to examine the materials of the present disclosure. Insome instances, the tissue-mimicking material for use in ultrasound hasthe same range of speeds of sound, attenuation coefficients, andbackscatter coefficients as the corresponding natural human tissue.Speeds of sound in human soft tissues is thought to vary over a fairlysmall range with an average value of about 1540 m/s, while the speed ofsound in fat is thought to be about 1470 m/s. The amplitude attenuationcoefficients in these tissues appear to vary over the range from about0.4 dB/cm to about 2 dB/cm at a frequency of 1 MHz.

Ultrasound phantoms are used to train medical personnel and to calibrateultrasound equipment. The phantom consists of targets imbedded in amatrix material. The targets are used to mimic features of the body suchas abnormal tissue, blood vessels and bone. The matrix may have severallayers that mimic the layers of tissue and fluids of the body. Medicalultrasound evaluations have recently employed techniques that determinethe flexibility of targets. This advancing technology is used todistinguish benign growths from cancerous tumors.

Mixtures of unfilled silicone gels (i.e., where silicone gel isunderstood to contain only siloxane and no fillers such as fused silicaor silicone oils) will successfully transmit ultrasound waves of commonfrequencies used in medical practices. The depth of penetration isgreater than 10 cm and much greater when the proper ultrasoundfrequencies are applied. The materials are tough, have high elongation(100% to 1000% at break) and can be made with a wide range offlexibilities. Silicone gels and silicones filled with silicone liquidsand fused silicones can be obtained from Factor II, AZ. An example of anunfilled silicone gel is Factor II A-341. An example of a filledsilicone is Factor II LSR-05. These materials are suitable for use asultrasound matrix and targets. In that regard, in some instances asilicone gel comprises 20-75% of the mixture, fused silica comprises0-50% of the mixture, and silicone fluid comprises 0-50% of the mixture.

The reflectivity of silicone targets can be adjusted to simulate varioustypes of human tissues and abnormalities. Silicone targets can be variedto create images that mimic soft to rigid tissues. The density andflexibility of silicone targets, and the corresponding reflectivity ofthe targets when visualized using ultrasound, is selectable by changingthe corresponding ratio of silicone gel, fused silica, and siliconeoils. Changing the bulk modulus and/or density (vs. the matrix)determines the strength of the echo. The greater this difference thegreater the reflection. The density of unfilled silicone thermosets(containing silicone gel, fused silica, and silicone oil) can vary fromapproximately a specific gravity of 0.9 to 1.5 g/cc. In one embodiment,the matrix material is formed of a Shore 0010 silicone and two targetsare positioned within the matrix material. The first target is formed ofShore 30 A silicone (silicone gel and fused silica) and the secondtarget is formed of Shore 0030 silicone (silicone gel, fused silica andsilicone oil). The two targets reflect differently under ultrasound. The30 A target will have greater reflection than the 0030 silicone target.The silicone gel/fused silica/silicone oil offers a wide range of bulkmodulus/density to facilitate a wide range of reflection strengthsrelative to a corresponding matrix material.

Targets can also be used within the silicone matrixes that do notcontain silicone. Examples of such targets are spaces within the matrixthat contain air, water, and/or saline solutions. In some instances,fluid filled spaces within the silicone matrix material are utilized torepresent blood vessels and/or other fluid filled organs of the bodysuch as cysts. Additional examples of non-silicone targets includethermoplastics and thermosets. The range of thermoplastics that can beused is almost unlimited: some examples are nylons, polyethylene,polyesters, styrene-ethylene-butylene-styrene and polyurethane.Thermosets include polyurethanes, latex, polysulfide, and variousepoxies. Silicone foams, such as those described herein, are used astargets in some instances. The foam can be used with or without siliconefluids and silicone thermosets. These closed cell foams are used torepresent highly reflective tissue such as bone and gas filled organs,in some instances.

Utilizing silicone materials as the matrix and targets of an ultrasoundphantom as described by the present disclosure are modifiable for use ina wide variety of ultrasound applications. In that regard, a greaterrange of reflection from the targets can be produced with non-filledsilicones than filled thermoplastics. The targets can be made torealistically mimic a broad range of tissues and abnormalities withoutthe need for non-silicone fillers. In some instances, increasedreflectivity is achieved by not applying a vacuum to the silicone duringproduction. In that regard, by not applying a vacuum to the silicone,the resulting targets will contain small pockets of air that increasethe reflectivity under ultrasound examination (See FIG. 35, forexample). Further, the silicone targets of the present disclosure arealso suitable for use within a matrix of other polymers such asthermoplastics.

A construction of silicone mixtures as layers and targets has advantagesover non-silicones and neat silicone gels. The silicone mixtures of thepresent disclosure, when properly formulated and cured, will bond toproperly formulated silicone targets or layers without adhesives. Thisallows the model to be layered without air gaps that can interfere withthe ultrasound imaging. In that regard, construction of phantoms isaccomplished in some instances by constructing a base layer of siliconematrix and then positioning targets on the layer then covering with thetargets and base layer with another layer of silicone matrix. Thismethod of construction facilitates the exact positioning of the targetswithin the phantom and results in the targets being bonded to thematrix, while preventing the formation of a layer of air around thetargets. Further, the filled silicone matrix of the present disclosureis significantly more durable than neat silicone gels.

In some instances, the inventive silicone mixtures of the presentdisclosure are used to manufacture biological tissue phantoms to trainmedical professionals and/or the general public. In one embodiment, themixtures are manufactured into tissue models for breast selfexamination. For example, referring now to FIGS. 1 and 2, shown thereinis a breast tissue model 100 according to one aspect of the presentdisclosure. In that regard, FIG. 1 is a front view of the breast tissuemodel 100, while FIG. 2 is a cross-sectional side view of the breasttissue model.

As shown in FIG. 1, the breast tissue model 100 includes a foundation102 from which a breast 104 extends. In that regard, the breast 104 issized and shaped to simulate a natural human breast. Accordingly, thebreast 104 will have different sizes and shapes in various embodiments.Specifically, the breast 104 may be sized and shaped to representnatural human breasts of varying cup size, age, medical condition, andother aspects. In some instances, the foundation 102 is sized and shapedto simulate the anatomy surrounding the natural human breast. The breast104 includes an areola 106 and a nipple 108. The areola 106 and thenipple 108 are similarly sized and shaped to simulate a natural humanareola and nipple. Accordingly, the areola 106 and/or the nipple 108will have different sizes and shapes in various embodiments. Within thebreast tissue model 100 are a plurality of simulated pathologies 110,which are illustrated in phantom. Generally, the pathologies 110 aresized, shaped, and have material properties to mimic various cysts,lumps, fibrous tissue, and other features found in natural breasttissue. In some instances, the pathologies mimic one or more of cysts,lumps, medullary carcinomas, ductal carcinomas, infiltrating scirrhuscarcinomas, lobular carcinomas, and fibroadenomas. While illustrated asbeing within the breast 104, in other embodiments one or morepathologies are present in the foundation 102 of the breast tissue model100 as well.

Referring more particularly to FIG. 2, the breast tissue model 100includes a backing 112 that supports the foundation 102 and the breast104. In the illustrated embodiment, the backing 112 is substantiallyplanar with a substantially constant thickness 114. It is understood,however, that the size and shape of the backing 112 as well as the sizeor footprint of the foundation 102 may be varied. In some instances, thebacking 112 and the foundation 102 are sized and shaped for positioningonto a base. Accordingly, in such instances, the backing 112 andfoundation 102 are sized and shaped to match an area of the base thatwill receive the breast tissue model 100. In some instances, the backing112 and/or the foundation 102 is contoured to accommodate for the shapeof the base such that when the breast tissue model 100 is positioned onthe base, the foundation 102 and the breast 104 together substantiallysimulate a natural human breast and the surrounding tissue. In thatregard, in some embodiments the backing 112 and/or the foundation 102 iscontoured to match the shape of a manikin or torso onto which the breasttissue model 100 will be mounted. Accordingly, it is understood that insome embodiments the thickness 114 of the backing 112 varies across thebacking. It is also understood that the thickness 114 of the backing mayvary greatly depending on an intended application for the breast tissuemodel 100.

In some instances, the manikin or torso includes a recess sized andshaped for receiving the breast tissue model 100. In one suchembodiment, an inner surface defined by the recess of the manikin ortorso is configured to mate with backing 112. As shown in FIG. 2, thebacking 112 includes a plurality of fasteners 116 extending therefrom.Releasable fasteners, such as hook and loop, snaps, buttons, ties, orany other suitable fastening device, may be used to selectively attachthe breast tissue model 100 to a base, including a manikin or torso. Thefasteners 116 are bonded to the breast tissue model 100 with an adhesivein some instances. In some instances, the adhesive is a cyanoacrylateand primer suitable for use on a silicon thermoset. Such adhesives arecurrently available from Loctite® Corporation. In other instances, thebreast tissue model 100 is molded or formed as part of the base (e.g.,as part of a female torso or manikin) and is, therefore, permanentlyattached to the base.

As shown in FIG. 2, the breast tissue model 100 includes a skin layer118 surrounding a fat or tissue layer 120. The skin layer 118 is formedof a silicone thermoset. Preferably, the silicone thermoset has asoftness and resiliency similar to natural human skin and has a shorehardness of equal to or lesser than 0010. One example of a suitablesilicone thermoset is Smooth-On Ecoflex® 0010. As shown, the skin layer118 has a thickness 122. In the illustrated embodiment, the thickness122 of the skin layer 118 is substantially constant across a majority ofthe breast tissue model 100. Generally, the thickness 122 of the skinlayer 118 is between about 1.0 mm and about 8.0 mm, and in someinstances is between about 2.0 mm and about 6.0 mm. The particularthickness of the skin may be selected in order to appropriately simulateparticular skin types and/or skin locations. As shown, however, anincrease in the thickness of the skin layer 118 is utilized to definethe areola 106 and the nipple 108. In other instances, the thickness 122of the skin layer 118 varies across the breast tissue model 100 in areasother than the areola 106 and nipple 108. In some embodiments, thebacking 112 is formed of the same material as the skin layer 118.Colorant is added to the silicone thermoset of the skin layer 118 inorder to simulate the natural colors of the skin, areola, and nipple.Also, adding colorant to the skin 118, areola 106, and nipple 108 of thebreast tissue model 100 prevents a user from being able to visualize theunderlying pathologies 110 within the breast tissue model. In thatregard, the particular colorant added to simulate the skin, areola, andnipple colors is selected to a match that of a particular ethnic groupin some instances. Generally, the skin, areola, and nipple colors of thebreast tissue model 100 may be selected to match the correspondingnatural skin, areola, and nipple colors of any ethnic group around theworld.

The tissue layer 120 of the breast tissue model is formed from a mixtureof silicone foam and silicone oil. Generally, the silicone foam ispresent in amount between about 10 percent and about 45 percent byweight of the total mixture weight, and the silicone oil is present inan amount between about 55 percent and about 90 percent by weight of thetotal mixture weight. In one particular embodiment, the mixture iscomprised of one part (or about 25 percent by weight) silicone foam,e.g., Smooth-On Soma-Foama® 15, and three parts (or about 75 percent byweight) silicone oil, e.g., BJB Enterprises TC-5005-C. The pathologies110 at the interface between tissue layer 120 and skin layer 122 areformed from a silicone thermoset. In some instances, the pathologies 110are formed from a silicone thermoset having a shore hardness of about 10A. An example of a suitable silicone thermoset for forming at least someof the pathologies 110 is Smooth-On Dragon Skin®. The silicon thermosetutilized for a particular pathology is dependent on the characteristicsof the pathology that is to be simulated. Accordingly, it is understoodthat various silicon thermosets having different properties may beutilized within a breast tissue model 100 in order to simulate differentpathologies.

The model 100 provides a means for teaching the techniques of breastexamination to detect breast abnormalities. In that regard, in someinstances the breast tissue model is particularly well suited forteaching proper techniques for detecting pathologies (e.g., cysts orlumps, including medullary carcinomas, ductal carcinomas, infiltratingscirrhus carcinomas, lobular carcinomas, and fibroadenomas) in thebreast with one's hands. In some instances, the model 100 is used toteach the spiral or grid patterns of palpation of the breast. In thismanner, the model 100 serves as an educational tool that can be used toteach users how to identify the signs and symptoms of breast cancer andother medical conditions. Through proper training with the devices ofthe present disclosure, earlier detection of breast cancer can befacilitated.

In some instances, a life size model of a human breast, typically withone or more lumps embedded in therein, is provided. In some instances,the breast tissue model is attachable to an upper part of a simulatedfemale torso or to a full size manikin to better simulate an actualexamination. In some instances, each breast includes a fastener orconnector that allows the breast to be selectively attached and detachedfrom the torso. Such detachable breasts allow for the use of breastswith different characteristics (e.g., number, size, and/or location oflumps) on the torso in order to better train users. In other instances,the breast tissue model is molded or formed as part of the female torsoor manikin and is, therefore, permanently attached to the torso. Duringthe examination, the torso to which the model is attached may be invertical, horizontal, or reclined position. The model of the humanbreast and the torso or manikin are easily shipped and readilytransportable.

Referring now to FIG. 3, shown therein is a breast tissue model system150 according to one aspect of the present disclosure. The breast tissuemodel system 150 includes a breast tissue model 152 and a breast tissuemodel 154. The breast tissue model 152 is substantially similar to thebreast tissue model 100 described above. In that regard, the breasttissue model 152 includes a foundation 156, a breast 158, an areola 160,a nipple 162, and pathologies 164 and 166. The structure of the breasttissue model 154 is substantially similar to the structure of the breasttissue model 152, such that the breast tissue model includes afoundation 168, a breast 170, an areola 172, a nipple 174, andpathologies 176 and 178 having substantially the same arrangement as thefoundation 156, breast 158, areola 160, nipple 162, and pathologies 164and 166. However, the breast tissue model 154 is formed without addingcolorant to the skin such that the pathologies 176, 178 are visiblethrough the skin. In that regard, the breast tissue model 154 istranslucent such that the pathologies 176, 178 positioned within thebreast 170 are visible to a user through the skin of the breast tissuemodel. To facilitate visual identification of the pathologies 176, 178,in some embodiments colorant is added to the materials forming thepathologies 176, 178 such that the pathologies 176, 178 contrast thesurrounding tissue material. As the breast tissue model 154 has the samestructure as the breast tissue model 152, the breast tissue model 154can be used to show users where the various pathologies within thebreast tissue model 152 are located and should have been detected. Thebreast tissue models 152, 154 may be provided together as a set suchthat the breast tissue model 152 may be considered the test model andthe breast tissue model 154 the corresponding key or answer model. Insome instances, the breast tissue models 152, 154 are provided as a pairof breasts, i.e., a left breast and a right breast. A specific exampleof the manufacturing of an embodiment similar to that shown in FIG. 3 isdescribed below in the Examples section.

To manufacture a breast tissue model in accordance with the presentdisclosure, a mold is first made. As discussed above, different breastsizes for different stages of life (ages) as well as shapes can bemanufactured. The mold generally defines the outside surface of theresulting breast tissue model. An initial model or master model thatwill serve as the basis for the mold can be sculpted, computergenerated, or reproduced from a live model. After the initial model ismade, a one piece silicone glove mold is made based upon the initialmodel. The glove mold is subsequently utilized to produce correspondingbreast tissue models. The glove mold may be formed from any suitablematerials. In some instances, a silicone thermoset with a hardnessgreater than or equal to 20 A is utilized as the glove mold. Examples ofsuitable glove mold materials include Smooth On Rebound® 25. Byutilizing a glove mold, the resulting product will not have a partingline. Also, the glove mold can be removed gently from the resultingproduct, thereby limiting any potential damage to the breast tissuemodel caused during removal from the mold. In some instances, a mothermold is utilized to surround and support the glove mold. The mother moldcan be made of any suitable thermoset material. In one embodiment, themother mold is formed of a hard polyurethane filled with aluminumparticles. In one embodiment, the mother mold is formed of Smooth OnC-1508®.

In some instances, the mother mold is manufactured in an alignment box.Once the alignment box is assembled, a shim is positioned and contouredover the glove mold. Clay openings are made between the shim and theglove mold. Polyurethane plastic, e.g., Smooth On C-1508®, is pouredinto half of the alignment box, and the shim is removed. Mold release isapplied to the plastic. A second pour of polyurethane plastic is madeand poured into the other half of the alignment box. The bottom of thealignment box is removed, and the alignment box split.

In some instances, an insert is also produced to help locate the lumpsin the model, and to provide a cavity to pour the silicone mixture into.To produce the insert, the glove mold is mounted in the mother mold. Alayer of clay is then sculpted on the interior of the glove mold. Thethickness of the clay layer defines the skin in the final breast tissuemodel. The clay is then marked at the positions that the lumps will belocated. The cavity is filled with a material to make the insert. Thematerial used to make the insert should be selected so the skin materialwill not stick and allow easy removal of the insert during production.In some instances, a hard polyurethane with aluminum particles oraluminum with Nedox® coating is utilized. Reference for alignmentbetween the insert and mother mold can be made at this time.

The silicone mixture can be different colors to represent areas of thebreast that are the most common places cancer is found. For example,internal parts of the breast can be a different color with muscles atthe back of the breast poured at different times as well as in differentdirections allowing for realism. In that regard, an upper portion of thebreast model can formed of a clear or translucent silicone, while thelower portion is formed of a colored silicone to illustrate the locationof the internal parts in relation to the outside of the breast. This issimilar to the concepts described above with respect to FIG. 3, wherethe silicone mixture of one of the breasts is colorless or translucent,to allow the pathologies within the breast tissue model to be seen.Further, the use of clear or translucent breast tissue model by itselfis advantageous in some instances, as it reduces the tendency of usersto simply poke the breast tissue model and encourages users to use theproper breast examination techniques instead of searching for the lumpsvia poking to receive instant gratification.

The silicone foam can be of different grades and cured at differenttemperatures or with different catalysts added to change the texture ofthe silicone. It is possible for each internal part of the breast tohave a separate mold. The parts could then be placed inside the breastmodel with clear silicone poured into the mold to fill and keep theinternal parts in place. The internal parts need not be made ofsilicone; other materials known to those of ordinary skill in the artcan be used as well. The resulting breast tissue model product isrealistic in appearance and has the proper feel to train individuals inthe proper techniques for inspecting the breast. The product can also beused with ultrasound equipment to visualize the lumps.

Referring now to FIG. 4, shown therein is a breast tissue model 200according to another aspect of the present disclosure. As shown, thebreast tissue model 200 includes a torso 202 with a left breast 204 anda right breast 206. Each of the left and right breasts 204, 206 includesa plurality of embedded anatomical features or pathologies. Inparticular, the left breast 204 includes six solid masses 208, 210, 212,214, 216, and 218 and three cysts 220, 222, and 224 positioned atvarious locations. The right breast 206 includes different cysts 226,228, 230, 232, 234, 236, 238, 240, 242, and 244 positioned at variouslocations. It is understood that fewer or a greater number ofpathologies may be utilized, the size and shape of the pathologies maybe modified, the positions (in three dimensions) of the pathologies maybe modified from the examples shown, and the types of pathologiesutilized may be modified. Further, it is understood that the pathologiesmay have irregular and/or geometrical shapes, depending on the type ofpathology being simulated. Despite the presence of the variousanatomical features within each of the left and right breasts 204 and206, the features are not visible when looking at the skin surfaces ofthe breasts. In some instances, the pathologies are colored the same orapproximately the same as the skin to prevent visualization of thefeatures through the skin without the use of ultrasound. Additionaldetails regarding the pathologies of the left and right breasts 204, 206are discussed below with respect to FIGS. 15-26 and in the context ofmanufacturing Example 3.

Referring now to FIGS. 5-14, shown therein are aspects of a moldingsystem 330 for forming a breast tissue model, such as breast tissuemodel 200 described above, according to embodiments of the presentdisclosure. Specifically, FIG. 5 is a perspective view of the moldingsystem; FIG. 6 is a perspective view of a mother mold 332 of the moldingsystem; FIG. 7 is a top view of the mother mold; FIG. 8 is across-sectional side view of the mother mold taken along section line8-8 of FIG. 7; FIG. 9 is a perspective view of a glove mold 334 of themolding system; FIG. 10 is a top view of the glove mold; FIG. 11 is aside view of the glove mold; FIG. 12 is a cross-sectional side view ofthe glove mold taken along section line 12-12 of FIG. 10; FIG. 13 is atop view of the mother mold and the glove mold assembled together; andFIG. 14 is a cross-sectional side view of the assembled mother mold andglove mold taken along section line 14-14 of FIG. 13.

Referring more specifically to FIGS. 6-8, aspects of the mother mold 332will be described. The mother mold 332 includes a main body 340 having agenerally rectangular shape. The body 340 includes a plurality ofrecesses or openings 342 that are configured to receive projections ofthe gantry 338 to facilitate proper alignment and assembly of the moldsystem 330, as will be discussed below. The mother mold 332 alsoincludes a recess or depression 344 that is sized, shaped, and contouredto simulate an outer surface of a natural breast and/or surroundingtissue. In that regard, the particular size, shape, and contour of thedepression 344 is selected based on the type (size, shape, age, etc.) ofbreast to be simulated. The mother mold 332 includes a rim 346 thatsubstantially surrounds the depression 344. In some instances, the rim346 is sized and shaped to interface with a portion of the glove mold334, as discussed below. Further, in some embodiments the mother mold332 includes a feature or structure to facilitate separation of theglove mold 334 from the mother mold 332. In the illustrated embodiment,the mother mold 332 includes cutout 348 that allows access to the glovemold 334 when the glove mold and the mother mold are assembled together.In some embodiments, the mother mold 332 is formed of machined aluminum6061 based on a model created using a 3D CAD system.

Referring more specifically to FIGS. 9-12, aspects of the glove mold 334will be described. As shown, the glove mold 334 includes a rim 350 thatdefines an outer boundary of the glove mold. In some instances, the rim350 is configured to interface with the rim 346 of the mother mold 332.The glove mold 334 also includes an inner surface 352 and an opposingouter surface 354. In some embodiments, the glove mold 334 is designedto follow simplified contours of a sculpted breast model. In thatregard, detailing may be simplified in the areola/nipple complex so thatthe outside surface 354 of the glove mold 334 includes smooth contoursand no undercuts. The internal geometry of the glove mold 334 as definedby the inner surface 352 replicates that of the sculpted breast model.Accordingly, products manufactured in the glove mold will be a replicaof that model. The depression 344 of the mother mold 332 is the negativeof the outer surface 354 of the glove mold 334 so that the glove mold334 and the mother mold will mate together. For example, as shown inFIGS. 13 and 14, when the glove mold 334 is mated with the mother mold332, the outer surface 354 of the glove mold is a generally perfect fitrelative to depression 344 of the mother mold. In that regard, in someinstances the glove mold 334 is manufactured within the mother mold 332such that the mother mold forms the outer surface 354 and a master moldforms the inner surface 352. The glove mold 334 is manufactured from aplatinum-cured silicone thermoset with a shore hardness between about 10A and about 30 A. In some instances, the material used for the glovemold is a silicone thermoset with a shore hardness of 10 A (e.g., DragonSkin® 10 Medium, Smooth-On, Inc., Easton, Pa.). The viscosity of thismaterial makes it a good choice for a glove mold as it allows easypouring and de-gassing of the material, with a cured flexibility thatcan be easily inverted to aid in product de-molding. Further, in theevent that the glove mold 334 is damaged, the design of the moldingsystem 330 makes it easy to replace the glove mold without having toreplace the mother mold 332 and/or other components of the system.Additional details of using the molding system 330 are discussed belowin the context of Example 3.

Numerous ultrasound renderings of ultrasound phantoms of the presentdisclosure will now be described. In that regard, the ultrasoundrenderings are based on ultrasound images obtained using a GE LOGIQ Bookwith a Linear Probe (Frequency of 8.0 MHz). However, it is understoodthat the ultrasound phantoms of the present disclosure may be utilizedwith virtually any type of ultrasound imaging devices. In that regard,in some embodiments the ultrasound phantoms of the present disclosureare particularly suited for calibrating ultrasound imaging devices. Inthat regard, because the ultrasound phantoms of the present disclosurehave known and substantially fixed material properties, the ultrasoundproperties of the phantoms are consistent. Accordingly, ultrasoundphantoms provide a consistent and repeatable ultrasound profile that maybe utilized for calibrating ultrasound imaging devices.

Referring now to FIGS. 15 and 16, shown therein are ultrasoundrenderings of an ultrasound phantom configured to simulate a solid massaccording to an embodiment of the present disclosure. In that regard,FIG. 15 is an ultrasound rendering of the ultrasound phantom, while FIG.16 is a close-up view of the solid mass of the ultrasound rendering ofFIG. 15. As shown in FIG. 15, a color change in the ultrasound rendering400 is indicative of a boundary or material change in the tissue. Asshown, the solid mass 402 has a lighter color compared to thesurrounding tissue. FIG. 16 is a close-up view of the solid mass 402taken from within box 404 of FIG. 15.

Referring now to FIGS. 17 and 18, shown therein are ultrasoundrenderings of an ultrasound phantom configured to simulate a translucentmass according to an embodiment of the present disclosure. In thatregard, FIG. 17 is an ultrasound rendering of the ultrasound phantom,while FIG. 18 is a close-up view of the translucent mass of theultrasound rendering of FIG. 17. In the ultrasound rendering 410 of FIG.17, a translucent mass is shown having an upper boundary 414 and a lowerboundary 416 as indicated by the change in color on the ultrasoundimage. FIG. 18 is a close-up view of the translucent mass 402 taken fromwithin box 418 of FIG. 17.

FIG. 19 is schematic diagram of an ultrasound phantom 380 according toanother embodiment of the present disclosure. Specifically, theultrasound phantom illustrates aspects of forming cysts in accordancewith aspects of the present disclosure. In that regard, the ultrasoundphantom 380 includes a first layer 382, a plurality of simulated cysts384, 386, and 388, and a second layer 390. Typically, the first andsecond layers 382, 390 will be formed of the same material, while eachof the cysts 384, 386, and 388 will be formed from a different material.In some particular instances, the first and second layers 382, 390 areformed of silicone and the cysts are a liquid (such as water).Accordingly, the formation of the silicone layers around the liquidcreates liquid filled pockets that simulate cysts. These cysts can beused within a patient simulator to allow training in the detection,biopsy, and/or aspiration of cysts. Typically, suspending liquids withthe desired properties to simulate abnormal tissue targets (such ascysts) within a silicone matrix has been problematic because the densityof the liquid is less than the density of the silicone matrix. Thepresent inventors have overcome this problem by utilizing the surfacetension properties of the liquid to hold the liquid in place duringsubsequent silicone pours.

In that regard, in some instances the following technique is utilized toform the simulated cysts. A mold is provided to shape the generalanatomical structure into which the cysts will be positioned.Accordingly, in some instances the mold is a breast mold. A layer ofsilicone (e.g., Smoothon Ecoflex 0010) is poured into the mold to form alayer of desired depth. Water from an eye dropper or syringe ispositioned on the surface of the silicone to form a simulated cyst ofthe desired volume in the desired location. The water displaces thesilicone and forms a well on the surface. After the silicone partiallycures or gels a second layer of silicone is slowly poured over theexisting surface to embed the water within the two silicone layers. Itis understood that other silicones and liquids with the appropriatephysical characteristic can be used. Also, it is understood that theliquid may be positioned within a well or depression in the first layerof material. Such a well or depression is formed using an insert mold insome instances. In that regard, the well or depression define at least aportion of the profile of the cyst in some instances.

Referring now to FIGS. 20 and 21, shown therein are ultrasoundrenderings of an ultrasound phantom configured to simulate a cystaccording to an embodiment of the present disclosure. In that regard,FIG. 20 is an ultrasound rendering of the ultrasound phantom, while FIG.21 is a close-up view of the cyst of the ultrasound rendering of FIG.20. In the ultrasound rendering 420 of FIG. 20, a cyst 422 is shownhaving an upper boundary 424 and a lower boundary 426 as indicated bythe change in color on the ultrasound image. FIG. 21 is a close-up viewof the cyst 422 taken from within box 428 of FIG. 20.

Because cysts of the present disclosure are formed, in some instances,by suspending a liquid within silicon, the cysts may be utilized totrain users on how to properly aspirate a cyst. Referring to FIGS.22-25, aspiration of the cyst 422 of FIGS. 20 and 21 will be discussed.In that regard, FIG. 22 is an ultrasound rendering showing theintroduction of a needle for aspirating the cyst; FIG. 23 is a close-upview of the cyst and needle of the ultrasound rendering of FIG. 22; FIG.24 is an ultrasound rendering of the ultrasound phantom showing thefully aspirated cyst; and FIG. 25 is a close-up view of the fullyaspirated cyst. As shown in the ultrasound rendering 430 of FIG. 22, aneedle tip 432 is introduced into the cyst 422 between the upper andlower boundaries 424, 426. In that regard, a user may rely on theultrasound visualization to ensure that the needle tip 432 haspenetrated the cyst 422. In this manner, the ultrasound phantom with thecyst 422 can be utilized to train medical personnel on the propertechniques for identifying the cyst and advancing a needle to the cystwith the aid of ultrasound. FIG. 23 is a close-up view of the needle tip432 positioned within the cyst 422 as shown within box 434 of FIG. 22.With the needle tip 432 positioned within the cyst 422, the fluid withinthe cyst can be extracted to aspirated. In some instances, a syringe isutilized to remove the fluid. In that regard, a user may translate aplunger of the syringe in order to aspirate the fluid from the cyst andinto the syringe. Other aspiration devices may also be utilized toremove the fluid. As shown in the ultrasound rendering 440 of FIG. 24,with the removal of the fluid from within the cyst 422, the upper andlower boundaries of the cyst have collapsed. FIG. 25 is a close-up viewof the collapsed cyst 422 as shown within box 442 of FIG. 24.

Referring now to FIG. 26, shown therein is an ultrasound rendering 450of an ultrasound phantom of the present disclosure showing the presenceof a plurality of cysts. In particular, the ultrasound rendering 450shows a cyst 452 towards the left side of the image and a cyst 454towards the right side of the image. Accordingly, it is understood thatwhen a ultrasound phantom containing numerous cysts is visualized usingultrasound, that the cysts may be simultaneously visible depending uponthe orientation of the ultrasound transducer relative to the cysts.

The materials of the present disclosure can be further refined for usein a variety of different medical ultrasound simulation applications,including central lines, catheterization, pericardial synthesis, andfetal ultrasound. By applying similar techniques and materials, it ispossible to represent a multitude of different tissue types. Forinstance, in the case of either central lines or catheterization, afluid-filled vessel is encapsulated within a tissue matrix. It ispossible to utilize the same matrix materials as utilized in themanufacturing techniques for the ultrasound breast models describedbelow. In that regard, the vessel can be manufactured in at least twoways. First, a vessel cavity can be incorporated in the matrix duringthe manufacturing process through the use of a removable pin/shaft whosediameter equals the internal diameter of the vessel. Second, a separatevessel wall can be manufactured in an injection mold from a siliconethermoset with a shore hardness different from that of the matrixmaterial. The vessel wall can then be embedded within the matrix todefine the vessel. A benefit of this second approach is that vesselswith varying elasticity and compressibility can be manufactured. Forexample, it allows representation of a vein versus an artery with thecorresponding varied geometry and compressibility. Examples of suchembodiments will now be described.

Referring to FIG. 27, shown therein is an ultrasound rendering 460 of anultrasound phantom for simulating a vessel according to another aspectof the present disclosure. In that regard, the ultrasound phantom allowsthe visualization of the simulated vessel using standard ultrasoundtechniques. As shown, the ultrasound rendering 460 shows an upper vesselwall boundary 462 and an opposing lower vessel wall boundary 464. Inthat regard, inner surface 466 and 468 of the upper and lower vesselwalls 462, 464, respectively, define the boundaries of lumen 470. Takentogether, the vessel walls 462, 464 and lumen 470 create a simulatedvessel.

Referring now to FIGS. 28-30, shown therein is a vessel simulator 500according to an embodiment of the present disclosure. Specifically, FIG.28 is a top view of the vessel simulator 500, FIG. 29 is an end view ofthe vessel simulator; and FIG. 30 is an end view of the vessel simulatorsimilar to that of FIG. 29, but showing deformation of a surface of thevessel simulator. As shown, the vessel simulator 500 includes a bodyportion 502 with two vessels 504 and 506 extending through the bodyportion. In the illustrated embodiment, the vessels extend entirelythrough the body portion and are substantially parallel to one another.In some instances, the vessels 504, 506 are configured to be coupled toa fluid supply system to that passes fluid, such as simulated blood,through the vessels. In such instances, the vessel simulator 500 can beused with Doppler ultrasound, where the flow of the fluid through thevessel is visualized on a screen (typically using color scales torepresent the speed of the fluid). For example, in some instances, thevessel 504 is configured to simulate a vein, while the vessel 506 isconfigured to simulate an artery. In that regard, the vessels 504, 506can be formed at varying depths relative to a surface 508 of thesimulator. In some instances, the surface 508 represents a skin layer ofthe patient. Accordingly, the depths of the vessels can be selectedbased on the particular vessels that are being simulated. As shown inFIG. 30, when the surface 508 of the vessel simulator 500 is depressed(e.g., during user palpation), the vessel 504 is compressed, therebysimulating a vein, while the vessel 506 generally maintains its shape,thereby simulating an artery.

Referring now to FIGS. 31 and 32, shown therein are ultrasoundrenderings of the vessel simulator similar to vessel simulator 500.Specifically, FIG. 31 is an ultrasound rendering of the vessel simulatorfrom a cross-sectional view, while FIG. 32 illustrates two ultrasoundrenderings of the vessel simulator from opposing side longitudinalviews. Referring more specifically to FIG. 31, the ultrasound rendering540 shows vessels 542 and 544. In that regard, vessel 542 has an upperboundary 546 and a lower boundary 548, while vessel 544 has an upperboundary 550 and a lower boundary 552 that are visible on the ultrasoundimage. Referring to FIG. 32, ultrasound rendering 560 shows vessel 542in the foreground, while ultrasound rendering 562 shows vessel 544 inthe foreground.

Referring now to FIG. 33, shown therein is a vessel simulator 570according to another embodiment of the present disclosure. In thatregard, vessel simulator 570 illustrates an example of a vesselsimulator where separate vessel walls have been utilized to define thevessels. In that regard, the vessel simulator 570 includes body portion572 and a pair of vessels 574 and 576. The vessels 574, 576 are definedby vessel walls 578 and 580, respectively. As discussed above, in someinstances the vessel walls 578, 580 are manufactured from a materialwith a shore hardness different from that of the body portion 572. Inthe illustrated embodiment, the vessel walls are embedded within thematrix material of the body portion 572 to define the vessels 574, 576.

Referring now to FIG. 34, shown therein is a vessel simulator 590according to another embodiment of the present disclosure. In thatregard, vessel simulator 590 illustrates an example of a vesselsimulator where the vessels are non-linear and do not extend entirelythrough simulator. In particular, the vessel simulator 590 includes abody portion 592 and a pair of vessels 594, 596. As shown, the vessels594, 596 have a non-linear profile and do not extend all of the waythrough the body portion. In that regard, while the vessels 594, 596 areshown as having the same profile, it is understood that each vessel mayhave a different linear and/or non-linear profile in other embodiments.

EXAMPLES

The invention is further defined by reference to the following examples,describing in detail the manufacture of the models of the presentinvention. These examples are for illustrative purposes only, and arenot to be construed as limiting the appended claims.

Example 1 Ultrasound Image—Target with Encapsulated Air

Referring to FIG. 35, shown therein is an ultrasound image of anultrasound phantom according to one aspect of the present disclosure. Inparticular, FIG. 35 illustrates an ultrasound rendering of an ultrasoundphantom comprised of 75% Factor II A341 and 25% LSR-05 and a SMOOTHONDragon Skin target with encapsulated air. The target is approximately 5mm×5 mm×10 mm in dimension. In that regard, each major marker on theimage scale is 1 cm. The resulting ultrasound image is consistent withan ultrasound image of bone. The ultrasound rendering of FIG. 35 is agray-scale representation of an actual ultrasound image obtained using aBard Site-Rite 3 Surface Probe ultrasound machine.

Example 2 Ultrasound Image—Target without Encapsulated Air

Referring to FIG. 36, shown therein is an ultrasound image of anultrasound phantom similar to that of FIG. 35, but illustrating anotheraspect of the present disclosure. In particular, FIG. 6 illustrates anultrasound image of an ultrasound phantom comprised of 75% Factor IIA341 and 25% LSR-05 and a SMOOTHON Dragon Skin target withoutencapsulated air. The target is approximately 5 mm×5 mm×10 mm indimension. Again, each major marker on the image scale is 1 cm and theresulting ultrasound image is consistent with an ultrasound image ofbone. The ultrasound image of FIG. 36 is also a gray-scalerepresentation of an actual ultrasound image obtained using a BardSite-Rite 3 Surface Probe ultrasound machine.

Example 3 Manufacturing Ultrasound Breast Simulator, Such as BreastModel 200 Described Above, with Medium Skin Tone

Manufacture of Dense masses (Material: Dragon Skin 10 Medium):

-   -   a. Measure 15 g of Part B, add 15 g Part A, 2 g URE-FIL 9    -   b. Mix and pour into silicone lump molds    -   c. Cure in a 100° C. Oven for 30 minutes

Breast Manufacture Pour 1 (Material: Silicone 99-255):

-   -   a. Clean the glove molds and liberally apply mold release    -   b. Measure 150 g Part B, add 8 drops (approximately 0.4 mL)        FuseFX Light Skin, 8 drops (approximately 0.4 mL) FuseFX Tan        Skin, 6 drops (approximately 0.3 mL) FuseFX Warm Rosy Skin, 150        g Part A    -   c. Mix and Vacuum until all bubbles are removed    -   d. Divide into equal volumes and pour into the left and right        glove molds    -   e. Immediately after pouring the silicone, fill an eye-dropper        with water, and dispense three cysts in the right breast and one        in the left. The cysts in the right breast are located in the        lower, outer quadrant, and their volume is approximately 1 mL.        The cyst in the left breast is located in the lower, outer        quadrant, and its volume is approximately 0.5 mL. The water        displaces the silicone and becomes encapsulated in the silicone.    -   f. After 45 minutes at room temperature, place two Dense Masses        in the left breast, 1 under the areola and a second directly        below that.    -   g. Let the breast stand for an additional 30 minutes at room        temperature before proceeding to Pour 2.

Breast Manufacture Pour 2 (Material: Silicone 99-255):

Note: Do not allow complete cure of the silicone between layers as thiswill prevent a uniform breast and may result in layering that is visibleunder ultrasound.

-   -   a. Measure 220 g Part B, add 11 drops (approximately 0.55 mL)        FuseFX Light Skin, 11 drops (approximately 0.55 mL) FuseFX Tan        Skin, 9 drops (approximately 0.45 mL) FuseFX Warm Rosy Skin, 220        g Part A    -   b. Mix and Vacuum until all bubbles are removed    -   c. Divide into equal volumes and pour into the left and right        glove molds    -   d. Immediately after pouring the silicone, fill an eye-dropper        with water, and dispense three cysts in the right breast and two        in the left. One cyst in the right breast is located in the        lower, outer quadrant (approximately 2 mL volume), the second in        the lower, inner quadrant (approximately 0.5 mL volume), and the        third directly south of the areola (approximately 0.5 mL        volume). One cyst in the left breast is located in the lower,        inner quadrant (approximately 1.5 mL volume), and the second        cyst is directly below the areola (approximately 0.5 mL volume)    -   e. After 45 minutes at room temperature, place two dense masses        in the left breast, both in the lower, outer quadrant.    -   f. Let the breast stand for an additional 30 minutes at room        temperature before proceeding to Pour 3.

Breast Manufacture Pour 3 (Material: Silicone 99-255):

-   -   a. Measure 300 g Part B, add 15 drops (approximately 0.75 mL)        FuseFX Light Skin, 15 drops (approximately 0.75 mL) FuseFX Tan        Skin, 12 drops (approximately 0.6 mL) FuseFX Warm Rosy Skin, 300        g Part A    -   b. Mix and Vacuum until all bubbles are removed    -   c. Divide into equal volumes and pour into the left and right        glove molds    -   d. Immediately after pouring the silicone, fill an eye-dropper        with water, and dispense three cysts in the right breast. Two        cysts are located in the lower, outer quadrant (approximately 1        mL volume each), and the third in the upper, outer quadrant        (approximately 1.25 mL volume).    -   e. Let the breast stand for an additional 1 hr 15 minutes at        room temperature before proceeding to Pour 4.

Breast Manufacture Pour 4 (Material: Silicone 99-255):

-   -   a. Measure 300 g Part B, add 15 drops (approximately 0.75 mL)        FuseFX Light Skin, 15 drops (approximately 0.75 mL) FuseFX Tan        Skin, 12 drops (approximately 0.6 mL) FuseFX Warm Rosy Skin, 300        g Part A    -   b. Mix and Vacuum until all bubbles are removed    -   c. Divide into equal volumes and pour into the left and right        glove molds    -   d. Immediately after pouring the silicone, fill an eye-dropper        with water, and dispense one cyst in the right breast in the        upper-outer quadrant (approximately 1.5 mL volume).    -   e. After 45 minutes at room temperature, place two dense masses        in the left breast, both in the axilla region.    -   f. Let the breast stand for an additional 30 minutes at room        temperature before proceeding to Pour 5.

Breast Manufacture Pour 5 (Material: Silicone 99-255):

-   -   a. Measure 300 g Part B, add 15 drops (approximately 0.75 mL)        FuseFX Light Skin, 15 drops (approximately 0.75 mL) FuseFX Tan        Skin, 12 drops (approximately 0.6 mL) FuseFX Warm Rosy Skin, 300        g Part A    -   b. Mix and Vacuum until all bubbles are removed    -   c. Divide into equal volumes and pour into the left and right        glove molds. Pour until the level reaches just below the height        of the Glove Mold    -   d. Allow it to cure for at least 4 hours, 8-12 hours if        possible, at room temperature.

Attach a strip of Loop Velcro, 8 inches in length:

-   -   a. Place a thin Layer of Sil-poxy on the back of Velcro, and        center the Velcro on the Back Skin of the Breast.    -   b. If necessary, place a flat board with weight to flatten the        Velcro.    -   c. Allow to cure for 30 minutes.

Gently remove the breast from the mold, and liberally clean any moldrelease from the surface.

Paint the coloring detail on the areola using blush-colored siliconepaint (FuseFX M-105 Blush). Cure in a 100° C. Oven for 30 minutes

Apply talc to the surface of the breast.

Cut an 8 inch length of Hook Velcro, and secure it on the Loop Velcro

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for other devices thatsimulate natural biological tissue, including human tissue. Inparticular, the materials and methods of the present disclosure may bereadily used in any application where the simulation of human skin, withor without underlying tissue structures, is desired. Such applicationsinclude, but are not limited to, manikins, sex toys, puppets, costumes,medical training devices, and/or other devices. In that regard, themethods described above for manufacturing the breast tissue models ofthe present disclosure may similarly be used with molds configured tomake other simulated human body portions, including any part or portionof the body having skin (e.g., arms, legs, hands, feet, torso, head,male genitalia, and portions thereof) as well as internal structures(e.g., heart, liver, kidneys, pancreas, stomach, colon, bladder, femalegenitalia, other internal organs, and portions thereof). Those skilledin the art should also realize that such equivalent constructions do notdepart from the spirit and scope of the present disclosure, and thatthey may make various changes, substitutions, and alterations to theembodiments disclosed herein without departing from the spirit and scopeof the present disclosure. Also, it will be fully appreciated that theabove-disclosed features and functions, and variations thereof, may becombined into other methods, systems, apparatus, or applications.

1. A method of creating an ultrasound phantom, comprising: pouring afirst silicone layer into a mold; introducing liquid onto the firstlayer; pouring a second silicone layer over the first layer and theliquid to encapsulate the liquid between the first and second siliconelayers.
 2. The method of claim 1, wherein the liquid encapsulated withinthe first and second silicone layers simulates a cyst.
 3. The method ofclaim 2, wherein the liquid encapsulated within the first and secondsilicone layers has a volume between about 0.1 ml and about 2.5 ml. 4.The method of claim 1, wherein the liquid is introduced into a recess inthe first silicone layer.
 5. The method of claim 4, further comprisingdefining the recess in the first silicone layer using an insert mold. 6.The method of claim 1, wherein the step of pouring the second siliconelayer is performed prior to curing of the first silicone layer.
 7. Themethod of claim 1, wherein the liquid is water.
 8. The method of claim7, wherein the first and second silicone layers are formed of a siliconegel.
 9. The method of claim 8, wherein the mold is shaped to simulateaspects of a human breast.
 10. The method of claim 1, furthercomprising: introducing liquid onto the second layer; and pouring athird silicone layer over the second layer and the liquid introducedonto the second layer to encapsulate the liquid between the second andthird silicone layers.
 11. The method of claim 10, wherein the firstsilicon layer defines a simulated skin layer.
 12. The method of claim11, wherein the liquid encapsulated within the first and second siliconelayers simulates a pathology positioned at a first depth relative to theskin layer and the liquid encapsulated within the second and thirdsilicone layers simulates a pathology positioned at a second depthrelative to the skin layer, the second depth being greater than thefirst depth.
 13. The method of claim 1, further comprising positioning asimulated dense mass onto the first silicone layer prior to pouring thesecond silicone layer.
 14. The method of claim 13, wherein the simulateddense mass comprises a silicone material having an increased durometerrelative to the first and second silicone layers.
 15. A human breasttissue ultrasound model comprising: a body portion sized and shaped tosimulate a human breast, the body portion including: a first siliconelayer; a second silicone layer; and a liquid suspended between the firstand second silicone layers to simulate a first pathology.
 16. The humanbreast tissue model of claim 15, wherein the first pathology is a cyst.17. The human breast tissue model of claim 16, wherein the first andsecond silicone layers and the liquid are configured to allow aspirationof the liquid from the body portion.
 18. The human breast tissue modelof claim 15, wherein the body portion further includes a third siliconelayer and a silicone material having an increased hardness relative tothe second and third silicone layers positioned between the second andthird silicone layers to simulate a second pathology.
 19. The humanbreast tissue model of claim 18, wherein the second pathology is a densemass.
 20. The human breast tissue model of claim 19, wherein the densemass is configured to allow biopsy of at least a portion of the densemass from the body portion.
 21. The human breast tissue model of claim19, wherein the first pathology is positioned at a first depth relativeto an outer surface of the body portion and the second pathology ispositioned at a second depth relative to the outer surface of the bodyportion, the second depth being greater than the first depth.